It is to be understood that the instant invention pertains to a machine for automatically measuring out an adjustably predetermined net weight amount of a loose and flowable dry particulate material and dispensing the same into a suitable container. In the foregoing respect, a loose and flowable dry particulate material would include but not necessarily be limited to powders such as various cosmetic, food, medicinal, and insecticide preparations; granular substances in the aforementioned categories; or any other of a number of substances which may be classified generally as being a loose and flowable dry particulate material.
In the merchandising of an increasing number of consumer products, many of which products are prepared in a loose and flowable dry particulate form, exemplary of which would be instant coffee or instant tea and the like, it has become a popular practice to package such products in containers such as wide mouth jars and the like whereby the products per se are highly visible to a consumer.
One of the problems encountered in the mechanical handling of loose and flowable dry particulate materials in accomplishing transport and measuring operations during container filling is vibration and abrasion of the material, with a resultant change in bulk density of the material. As a consequence of reduced bulk density of said material resultant from the aforementioned effects, which causes aeriation thereof, in order to dispense a certain net weight amount of said material into a container it becomes necessary to employ a larger volume container than would otherwise be necessary if one were dispensing a certain net weight amount of the subject material when not in the aerated and reduced bulk density state. Under the foregoing circumstances, after container filling and during handling and shipping operations the subject material compacts within the container to its normal bulk density with a resultant receding of the fill line from the neck of the container thereby giving the visual impression that there has been only a partial fill when in fact there is a proper net weight amount of the subject material in the container.
Another factor to be considered is that products of the type aforementioned are sold on a net weight basis, and in view of the strictly monitered and enforced sanctions against merchandisers who sell less than the net weight amount of product indicated on the container label, it is advisable that at least the net weight amount of product indicated on the label be in the container.
The expedient most frequently employed to overcome both the receding fill line effect due to reduced bulk density, as well as insuring that at least the net weight amount of product as indicated on the label is in the container, is to overfill the container, thereby resulting in the "giving away" of a certain amount of saleable product which would not otherwise be the case if net weight filling equipment were available with the mechanical capability of handling loose and flowable dry particulate materials without causing the aeration effect aforementioned and thus a reduction in bulk density, and also having the additional capabilities of providing accurate consistently repeatable predetermined net weight measuring and dispensing of said materials at speeds necessary to meet production demands.
Another factor which affects the accuracy of net weight filling operations turns on whether the material being handled and weighed is susceptible to absorption of atmospheric moisture, which not only has the effect of also changing the bulk density thereby resulting in loss of real product weighing accuracy, but additionally tends to cause agglomeration of the material to such an extent that the otherwise loose and flowable characteristics thereof are lost thereby resulting in machine fouling and various other detrimental machine effects.
The nature of the material being handled must also be considered, as in the case of insecticides, with respect to worker safety in and around the machine area. If the material to be handled is easily dusted off and of a hazardous nature the net weight filling machine configuration should provide a closed structure.
Among the prior art disclosures wherein net weight filling machines are taught, U.S. Pat. No. 2,089,534 to Carlson, dated Aug. 10, 1937, shows a bag filling mechanism which is in some respects structurally similar to the instant invention, and which incorporates a balance beam counter-balanced to the net weight measuring receptacle plus the weight of material to be measured out, however, no other teachings in Carlson are per se similar to the additional featues taught by the instant invention.
The disclosure shown in U.S. Pat. No. 2,138,356 to Ryan et al, dated Nov. 29, 1938, teaches a closed system net weight filling machine featuring a selected atmosphere environment capability, otherwise, being distinguished from the instant invention. The disclosure shown in U.S. Pat. No. 2,684,803 to Birkland et al, dated July 27, 1954, likewise teaches a closed system net weight filling machine featuring a vacuum environment capability in addition to a mechanically activated balance beam counter-balanced to the net weight measuring receptacle plus the weight of material to be measured out, and, again, otherwise distinguished from the instant invention.
As heretofore pointed out the subject of the instant invention comprises a machine which incorporates features that provide a new and novel mechanical means for automatically handling, net weighing, and dispensing into suitable containers a wide range of various substances generally classed as loose and flowable dry particulate materials wherein said instant invention is distinguishable from the prior art inventions in one or more ways in that said instant invention has utility features and new and useful advantages, applications, and improvements in the art of net weighing operations not heretofore disclosed, as set forth hereinafter.